Recovery of 1,1-dihydroheptafluorobutanol from water by distillation

Abstract

Esters are treated with alkali metal borohydride to produce alcohols. Substantially constant boiling admixtures of: methanol/methyl heptafluorobutyrate, water/1,1-dihydroheptafluorobutanol, and water/methyl heptafluorobutyrate are described.

I claim: 
     
       1. A substantially constant boiling admixture of water and 1,1-dihydroheptafluorobutanol characterized by a boiling point of about 83°-85° C. at substantially atmospheric pressure. 
     
     
       2. The substantially constant boiling admixture according to claim 1 characterized by about 78 weight percent 1,1-dihydroheptafluorobutanol and about 22 weight percent water. 
     
     
       3. The substantially constant boiling admixture according to claim 1 characterized as a minimum boiling azeotrope. 
     
     
       4. A process for removing water from a mixture comprising water and 1,1-dihydroheptafluorobutanol which comprises the steps of: (a) distilling said mixture comprising water and 1,1-dihydroheptafluorobutanol to produce an overhead water/1,1-dihydroheptafluorobutanol azeotrope.   (b) condensing said azeotrope,   (c) cooling said condensed azeotrope, thereby effecting a phase separation into a light predominantly aqueous liquid phase, and a heavy predominantly organic liquid phase, and   (d) returning said heavy predominantly organic liquid phase to said step (a) until the water content in the original mixture of said step (a) is substantially exhausted.   
     
     
       5. The process according to claim 4 wherein said condensed azeotrope is cooled to a temperature in the range of about -20° C. to about 80° C. employing sufficient pressure to maintain substantially liquid phase conditions.